In the latest development in a massive Ecuador environmental case that has put lawyers who won a $9.5 billion verdict for the plaintiffs under unusual pressure, Patton Boggs has agreed to withdraw from the case and pay $15 million to Chevron Corp.

Although Patton Boggs was not lead counsel in the case, the well-known Washington, D.C.-based firm agreed to help lead sole practitioner Steven Donziger of New York collect the $9.5 billion judgment awarded by a court in Ecuador against Chevron. A federal judge in New York earlier this year blocked collection of the judgment, finding in a civil racketeering case brought by Chevron that the $9.5 billion verdict was “obtained by corrupt means.” Later than month, U.S. District Judge Lewis A. Kaplan ruled that Chevron could sue Patton Boggs over its collection role.

That resulted in a decision by Patton Boggs, announced today, to withdraw from the case and settle with Chevron, reports Bloomberg.

“The recent opinion of the United States District Court for the Southern District of New York in the Chevron v. Donziger case includes a number of factual findings about matters which would have materially affected our firm’s decision to become involved and stay involved as counsel here,” said the firm in a statement included in the settlement agreement. “Based on the court’s findings, Patton Boggs regrets its involvement in this matter.”

Hewitt Pate, who serves as vice president and general counsel of Chevron, said in a press release that the company is “pleased that Patton Boggs is ending its association with the fraudulent and extortionate Ecuador litigation scheme. Chevron detailed its objections to Patton Boggs’ conduct in its counterclaim, and today’s agreement brings that litigation to an end. Chevron encourages others to disassociate themselves from this fraud.”

Donziger is appealing Kaplan’s decision in the civil racketeering case. He discussed his position earlier in a 63-page witness statement (PDF).